The invention concerns a flange driver intended for the U-joint of a cardan shaft and comprised of two mutually complementary yoke halves.
Embodiments of split flange drivers are previously known, for instance from the German G 93 15717.7 and EP 0 206 026. Cardan yokes of split design enable the construction of integral and dimensionally stable bearing eyes which, the same as in an undivided yoke, remain an integral part of the adjoining yoke arm by way of which the force is transmitted to the bearing eye. In this way there occurs no interruption of the flow of force at the specifically most stressed point of the yoke. Arranged in the plane of symmetry between the eyes of the yoke, the parting point is situated in the area of lowest stress, which has no effect whatsoever on the transmission of force. These arrangements offer the advantage of a sound bedding of the bearing in the eye, of a very easy assembly and an increased load capacity of the bearing. At the same time, split yokes offer considerable advantages in their manufacture, processing, shipping and storage.
In detail, there are various engineering options for torque transmission known, to achieve the transmission of force between the input and output shafts. The yoke halves styled as described in EP 0 206 026 feature each a flange which on its side away from the spider axis possesses positive-locking elements, so that a positive connection is established with the driven shaft or the shaft being driven. Additionally there are releasable connections provided between the flange and the respective shaft, for example by means of antifatigue-shaft bolts.
The interfaces of the yoke halves are arranged here essentially mutually parallel and feature opposed keyways in the center area. Keys of square shape are inserted in these keyways. They serve primarily to prevent the yoke halves from shifting mutually parallel to the axis of the spider pin mounted in the yoke. Avoiding a relative motion of the yoke halves perpendicularly to the spider pin axis, i.e., in the direction of the yoke axis, is not feasible with this solution; neither can the yoke halves be prestressed relative to each other. The result, especially in reverse operation, is a lift-off of individual areas of the yoke halves under the effect of the peripheral force. The lift-off also causes a relative motion of the positive-locking elements onto the recesses in the adjoining shaft, which--in turn--leads to the creation of voids which allow the accumulation of moisture and seepage water. The result are corrosion phenomena, which are promoted yet by the micromotion of the yoke halves.
In the styling described in G 93 15 717.7, the two yoke halves are joined by means of a positive-locking joint and feature, common to both yoke halves, a system for torque transmission from the shaft adjoining the cardan joint to the flange driver and spider, respectively also in reverse order. The embodiments proposed in G 93 15 717.7 for a positive-locking joint are, in part, very manufacturing- and assembly-intensive.
Therefore, the problem underlying the invention is to further advance a flange driver of the initially named kind to the effect that the cited drawbacks will be avoided while maintaining a favorable design of the flange driver for accommodating the bearing and achieving maximally high bearing forces, the same as in the unpublished G 93 15 717.7, and that a low-cost manufacture with effective utilization of existing capacities and an easy assembly are accomplished. A further essential problem consists in achieving at low cost an optimum seal so as to avoid fretting corrosion and other corrosion phenomena closely associated with the problem, which, in turn, favors a long service life of the flange drivers.